The case of school groundskeeper Dewayne Johnson was the first lawsuit alleging glyphosate causes cancer to go to trial.

Johnson's case, filed in 2016, was fast-tracked for trial due to the severity of his non-Hodgkin's lymphoma, a cancer of the lymph system that he alleges was caused by Roundup and Ranger Pro, another Monsanto glyphosate herbicide. Johnson's doctors said he is unlikely to live past 2020.

Chemical giant Monsanto has been ordered to pay $289m damages to groundskeeper Dewayne Johnson who claimed herbicides containing glyphosate had caused his cancer. Working for a school district in Benicia, California, about 40 miles east of San Francisco, Mr Johnson mixed and sprayed hundreds of gallons of Roundup.

In a landmark case, a Californian jury found that Monsanto knew its Roundup and RangerPro weedkillers were dangerous and failed to warn consumers. It's the first lawsuit to go to trial alleging a glyphosate link to cancer.

Following an eight-week trial, the jury ordered the agricultural multi-national to pay $250m in punitive damages together with other costs that brought the total figure to almost $290m. Jurors in state Superior Court agreed the product contributed to Johnson's cancer and the company should have provided a label warning of the potential health hazard Mr Johnson was diagnosed with non-Hodgkin's lymphoma in 2014. His lawyers said he regularly used a form of RangerPro while working at a school in Benicia, California.

"This jury found Monsanto acted with malice and oppression because they knew what they were doing was wrong and doing it with reckless disregard for human life," said Robert F. Kennedy Jr., a member of Johnson's legal team. "This should send a strong message to the boardroom of Monsanto."

Monsanto scientists knew of the cancer risk posed by Roundup as far back as the 1970s, but failed to inform the public and instead engaged in a "deliberate effort to distort the truth” as the weedkiller generated hefty returns, Mr Johnson’s lawyer, Brent Wisner, told the jury in closing arguments on Tuesday.

“Monsanto made a choice to not put a cancer warning on the label,” Mr Wisner said. “That is a choice that shows their reckless disregard for human health, and today is their day of reckoning.”Brent Wisner, a lawyer for Johnson, in a statement said jurors for the first time had seen internal company documents "proving that Monsanto has known for decades that glyphosate and specifically Roundup could cause cancer." He called on Monsanto to "put consumer safety first over profits."

Monsanto in a statement said it would appeal the verdict.

Another Roundup cancer trial is scheduled to begin in the fall in St Louis, Missouri. According to Johnson’s lawyers, Monsanto is facing more than 4,000 similar cases across the US.

In 2015 the International Agency for Research on Cancer, the World Health Organisation's cancer agency, concluded that it was "probably carcinogenic to humans".